The present invention relates generally to semiconductor etch processes, and more particularly, to methods and systems for cleaning the etch process chamber.
Semiconductor wafers are typically placed in an etch chamber with a photoresist mask layer to direct the etch of the underlying materials. The etching process removes the underlying materials not covered by the photoresist. The etch process also removes a portion of the photoresist.
The etch byproducts including mixtures of the etchant chemicals, the photoresist and the underlying materials, condense on the walls and any other surface within the etch process chamber. Typically, an oxygen based plasma waferless cleaning process is used to volatilize the etch byproducts. The volatilized etch byproducts can then be evacuated or purged from the etch process chamber.
As the device sizes have become smaller, the materials in the mask layer have changed to hard mask materials including metals such as titanium and others. The titanium in the mask layer is etched away from the wafer and condensed on the walls and other surfaces within the etch process chamber. However, the oxygen based plasma waferless cleaning process is very slow and inefficient at volatilizing the titanium containing residue from the inner surfaces of the etch process chamber. As a result, the titanium containing etch byproducts tend to build up on the inner surfaces of the etch process chamber. Eventually, the titanium containing etch byproducts can flake off the inner surfaces of the etch process chamber and cause excessive particles on the wafer.
There is a need for a more efficient waferless cleaning process that will effectively remove the deposited mixture of titanium, photoresist and underlying materials without damaging the surfaces and devices within the etch process chamber.